Newsgroups: alt.engineering.electrical
Subject: Re: Dimmer for low voltage halogen desk lamp.
References: 
**THE-RFI-EMI-GUY**  writes:

> I have a couple of these low voltage halogen desk lamps by the bed. My
> wife wants to put a dimmer on hers. These lamps have a 120-12V
> transformer in the base and a diode for dimming down one level. I have
> replaced the 50 watt bulbs with the lowest power I could find, (I
> think 25 w), but still not enough.
> 
> I know a standard dimmer won't work with the transformer. 

Most normal dimmers are not designed to work well with highly 
inductive loads like traditional transformers. 

Electronic transformers used on many modern low voltage 
halogen light systems. Those are switch mode power supplies. 
Dimmign them varies from not dimmable, to dimmable with 
special dimmer to dimmable with normal dimmer.    

> Is there an
> off the shelf dimmer that will work? 

I don't know what is "off the shelf" in USA where you live. 

> If not what could be suggested as
> far as an inexpensive and compact autotransformer? 

Autotransformer method will work with halogen lights that
use normal traditional transformer. 

The dimming range that you cam get with adjustable 
autotransformer with "electronic transformers" can 
vary from quite useable to not workign very well 
depending on the "electronic transformer" type.   

> I was thinking an
> isolation transformer wired in a "buck" configuration. I don't think I
> need a variable. Any pointers? 

-- 
Tomi Engdahl (http://www.iki.fi/then/)
Take a look at my electronics web links and documents at 
http://www.epanorama.net/